Maxima Function
featurep (a, f)
Attempts to determine whether the object a has the
feature f on the basis of the facts in the current database. If so,
it returns true, else false.
Note that featurep returns false when neither f
nor the negation of f can be established.
featurep evaluates its argument.
(%i1) declare (j, even)$ (%i2) featurep (j, integer); (%o2) true